Traditionally, in gypsum wallboard or "drywall" panel installation, sheets of drywall are nailed or screwed in place. Seams between the drywall sheets must be taped over, and the nail or screw heads must be coated with paper tape and mastic material to form a continuous wall surface. Tape and mastic material must also be applied to inside corners to form a complete wall system. The task of applying drywall tape and mastic drywall mud is generally laborious, tedious, and messy. Although inventions have made the task easier, improvement is still needed. One currently available drywall taping tool is the pedestrian mud pan and drywall knife.
With a mud pan and drywall knife, a workman manually applies drywall tape and mud. First, the workman removes a scoop of mud from a bulk container in a mud supply area and places it in the mud pan. This action is repeated until the pan is full. The workman then walks from the mud supply area to the seam that he wishes to tape. The workman then scoops a quantity of mud onto the knife, turns the knife blade towards the wall, and with a series of wiping motions, coats the seam with mud more or less uniformly. After precutting the seam, the workman lays paper tape over the seam and presses it into the mud to achieve tape attachment. He then glides the knife over the tape, forcing mud and air out from behind the tape, and begins to smooth the surface. A first coat of mud is applied to the drywall tape either at the time that the tape is applied or later, depending on the workman's technique.
After a period of drying, another coat of mud is applied to the tape and dressed with a drywall knife, thus covering the seam with a wider coat of mud. The same steps of walking to the mud supply area, scooping out mud until the pan is full, and then walking back to the work area are repeated.
After a second period of drying, most inexperienced workmen sand the seams before applying a final coat of mud. The final coat of mud requires further walking between the mud supply and the work areas and further scooping and filling of the mud pan as before.
Complicating the situation are inside corner seams. Most workmen find inside corner seams the hardest and most time consuming to tape and coat of any seam. There are special knives that have a ninety degree bend to help dress these difficult seams.
To overcome the drawbacks of manual drywall tape application and finishing tools such as the mud pan and drywall knife, a drywall taping system has been developed by Ames Tool Company (Ames), for example, that includes a manual, lever action, fluid mud pump that fills assorted mud applicator tools. A hand lever on the manual pump is pumped up and down to transfer drywall mud out of a bucket directly into a mud applicator tool. The mud is squirted into a slot in some tools and into other tools though a special fitting.
However, this system still requires walking between the mud supply and work areas, thus wasting time and energy. Only about ninety feet of tape can be applied with the Ames taper tool before a mud refilling is required, while each roll of paper tape is about 500 feet. Only about three to four vertical seams, where each seam is about eight feet long, can be filled with the Ames box tools before more mud is required. Thus, a day's work requires hundreds of trips between the mud supply and work areas for mud refills with the Ames drywall taping system.
Additionally, each of the tools in the Ames system takes some toll upon the user's energy. The Ames taper tool is powered by the user forcing a wheel to turn as it contacts the wall at the end of the tool. The Ames box tool requires the operator to forcefully wipe a box of mud on an extended handle. Each of the Ames tools mechanically disgorge drywall mud as the result of human labor. Many tasks in drywall taping are thus prone to repetitive stress injury.
Furthermore, Ames tools require both a reservoir that holds one shot of mud and a device to manually exude the mud on each tool. The Ames system is expensive, heavy, and manually actuated.
The stators tube pump is well known to the drywall industry. This pump has a hollow threaded internal rubber sleeve encompassing a threaded rod. As the rod is turned, fluid drywall material is forced to exit the pump. However, the stators pump requires an electric motor or gas engine to operate and is thus expensive to build. The stators pump is also very inefficient due to friction, so a large power source is required. Therefore, fluid material delivery systems using a stators pump for drywall work are expensive.